藍帶血月
A Blue Banded Blood Moon
來源：Zixiong Jin｜發表日期：2025-03-25
月食期間，是什麼原因導致藍色條帶穿過月球？藍帶是真實存在的，但通常很難看到。然而，上週月食的 HDR 影像（拍攝於美國俄克拉荷馬州諾曼市）經過數字處理，誇大了色彩。 上圖右上方的灰色是月球的本色，由陽光直接照射。三幅影像中月球的下半部分都沒有被太陽直接照亮，因為它正處於日食狀態--處於地球的陰影中。不過，它被穿過地球大氣層深處的陽光微弱地照亮了。月球的這一部分是紅色的，被稱為 "血月"，其原因與地球上的日落是紅色的一樣：因為空氣散射掉的藍光比紅光多。上圖和中圖右上方可見的不尋常的紫藍色條帶則不同--它的顏色是由高空穿過地球大氣層的太陽光增加的，在地球大氣層中，紅光比藍光更容易被臭氧吸收。 天體驚喜你的生日那天，APOD 刊登了哪張照片？ （ 1995 年後）
原文：What causes a blue band to cross the Moon during a lunar eclipse? The blue band is real but usually quite hard to see. The featured HDR image of last week's lunar eclipse, however -- taken from Norman, Oklahoma (USA) -- has been digitally processed to exaggerate the colors. The gray color on the upper right of the top lunar image is the Moon's natural color, directly illuminated by sunlight. The lower parts of the Moon on all three images are not directly lit by the Sun since it is being eclipsed -- it is in the Earth's shadow. It is faintly lit, though, by sunlight that has passed deep through Earth's atmosphere. This part of the Moon is red -- and called a blood Moon -- for the same reason that Earth's sunsets are red: because air scatters away more blue light than red. The unusual purple-blue band visible on the upper right of the top and middle images is different -- its color is augmented by sunlight that has passed high through Earth's atmosphere, where red light is better absorbed by ozone than blue. Celestial Surprise: What picture did APOD feature on your birthday? (post 1995)
※ 本文由萌芽機器人自動轉貼自每日一天文圖（Astronomy Picture of the Day，APOD），原文為英文，正體中文是透過 DeepL 翻譯及 OpenCC 進行自動處理，內容僅供參考，若有任何錯誤之處還請見諒！
關於每日一天文圖：每日一天文圖網站是美國國家航空暨太空總署與密西根理工大學提供的服務，網站每天提供一張影像或圖片，並由天文學家撰寫扼要說明其特別之處。